Maximum Polarization Research Articles

Crystal symmetry transition and its influence on optical, dielectric, and ferroelectric properties in (1-x)Na0.5Bi0.5TiO3-xSrTiO3 system

Ferroelectric perovskites materials are the most promising materials because of their multifunctional applications as well as the ongoing fundamental research on them. The present study investigates the correlation between the crystal structure and various physical properties such as dielectric, ferroelectric, and optical properties of Sr2+ modified Sodium bismuth titanate Na0.5Bi0.5−xSrxTiO3 (x = 0.00, 0.02, 0.04, and 0.06) synthesized by solid-state reaction method. Rietveld refinement of the X-ray diffraction pattern reveals that the system undergoes a crystal symmetry transition from a two-phase crystal symmetries system (rhombohedral (R3c) and tetragonal (P4bm)) to a three-phase crystal symmetries system (rhombohedral (R3c), tetragonal (P4bm) and Cubic (Pm3̅m)) with the rise in Sr2+ concentration in Na0.5Bi0.5−xSrxTiO3 which is the foremost reason behind the variation of physical properties of the system. The dielectric constant and maximum polarization increase with the Sr2+ concentration up to 2% and it decreases with the further increase in Sr concentration due to the distortion in crystal structure induced by the introduction of cubic phase (Paraelectric) in the system. The maximum value of the dielectric constant is estimated to be 3629 at a low frequency on the Na0.50Bi0.48Sr0.02TiO3 system. The optical band gap (Eg) of Na0.5Bi0.5−xSrxTiO3 (x = 0.00, 0.02, 0.04, and 0.06) ceramics are found to vary between 3.202 eV to 3.172 eV which indicates the semiconducting nature of prepared samples but urbach energy shows an opposite behaviour i.e. increases with Sr concentration.

A polarization double-enhancement strategy to achieve super low energy consumption with ultra-high energy storage capacity in BCZT-based relaxor ferroelectrics.

Due to dielectric capacitors' already-obtained fast charge-discharge speed, research has been focused on improving their Wrec. Increasing the polarization and enhancing the voltage endurance are efficient ways to reach higher Wrec, however simultaneous modification still seems a paradox. For example, in the ferroelectric-to-relaxor ferroelectric (FE-to-RFE) phase transition strategy, which has been widely used in the latest decade, electric breakdown strength (Eb) and energy storage efficiency (η) always increase, while at the same time, the maximum polarization (Pmax) inevitably decreases. The solution to this problem can be obtained from another degree of freedom, like defect engineering. By incorporating Bi(Zn2/3Ta1/3)O3 (BZT) into the Ba0.15Ca0.85Zr0.1Ti0.9O3 (BCZT) lattice to form (1 - x)Ba0.15Ca0.85Zr0.1Ti0.9O3-xBi(Zn2/3Ta1/3)O3 (BCZT-xBZT) solid-solution ceramics, in this work, ultrahigh ferroelectric polarization was achieved in BCZT-0.15BZT, which is caused by the polarization double-enhancement, comprising the contribution of interfacial and dipole polarization. In addition, due to the electron compensation, a Schottky contact formed at the interface between the electrode and the ceramic, which in the meantime, enhanced its Eb. A Wrec of 8.03 J cm-3, which is the highest among the BCZT-based ceramics reported so far, with an extremely low energy consumption, was finally achieved. BCZT-0.15BZT also has relatively good polarization fatigue after long-term use, good energy storage frequency stability and thermal stability, as well as excellent discharge properties.

Identifying routes for transferring spin polarization from parahydrogen to protic solvents.

Repeatable hyperpolarization of high concentrations of mobile protons (>6 M) using parahydrogen in protic methanol/water mixtures is reported here. Different ammonium buffers with increasing mobile proton concentrations were added to an IrCl(COD)(IMes) catalyst in the presence of pyridine. We reach a maximum molar polarization of 1.79 mM at 6 mT. Field-cycling experiments in an 18.8 T detection field distinguished two solvent polarization transfer pathways: chemical exchange with labile protons from ammonia and cross-relaxation with pyridine aromatic protons.

Achieving high energy storage density at low operating fields in lead hafnate-based novel perovskite solid solutions

Schematic diagram illustrating the concept, approaches and goal in the design and preparation of a new solid solution system (1 − x)PbHfO3–xAgNbO3, with enhanced maximum polarization and recoverable energy storage density at low operating fields.

Relaxation enhancement by microwave irradiation may limit dynamic nuclear polarization.

Dynamic nuclear polarization enables the hyperpolarization of nuclear spins beyond the thermal-equilibrium Boltzmann distribution. However, it is often unclear why the experimentally measured hyperpolarization is below the theoretically achievable maximum polarization. We report a (near-) resonant relaxation enhancement by microwave (MW) irradiation, leading to a significant increase in the nuclear polarization decay compared to measurements without MW irradiation. For example, the increased nuclear relaxation limits the achievable polarization levels to around 35% instead of hypothetical 60%, measured in the DNP material TEMPO in 1H glassy matrices at 3.3 K and 7 T. Applying rate-equation models to published build-up and decay data indicates that such relaxation enhancement is a common issue in many samples when using different radicals at low sample temperatures and high Boltzmann polarizations of the electrons. Accordingly, quantification and a better understanding of the relaxation processes under MW irradiation might help to design samples and processes towards achieving higher nuclear hyperpolarization levels.

Optimization of switching charge and recoverable energy density mediated by structural transformation in Sr-substituted BaNiO3 perovskites.

Because of their distinctive characteristics, ferroelectric perovskites are considered among the most potent and auspicious candidates for energy storage and pulsed power devices. But their energy storage properties and switching capabilities need to be further enhanced which can be done by substitutions of appropriate cations. Hence, a series of lead-free Ba1-xSrxNiO3 (x = 0.00, 0.33, 0.67, and 1.00) ceramics was fabricated using a sol-gel auto combustion technique. Rietveld's refinement of X-ray diffraction plots verified the complete development of the required hexagonal perovskite structure. Scanning electron microscopy images revealed a gradual increase in average grain sizes and agglomeration with the increase in Sr-content. Moreover, the existence of all the constituent elements exactly in proportion to their stoichiometric ratios was verified by energy dispersive X-ray spectroscopy. The characteristic parameters of ferroelectric materials such as ferroelectric response, electrical conductivity, and switching charge density were also determined. The P-E loops indicated that with the increase in Sr-content, the coercive field, remanent polarization, and maximum polarization all decreased gradually, but the recoverable energy density (Wrec) increased as the loops became slimmer. The maximum value of Wrec was found in the Ba0.33Sr0.67NiO3 sample. Moreover, SrNiO3 exhibited minimum energy loss with the highest efficiency of ∼47.21%. The existence of a current barrier in all the samples was proved from the low leakage current values (∼10-7 A). In addition, the pure SrNiO3 showed a low electrical conductivity and minimum value of switching charge density. All these findings make SrNiO3 a promising candidate for fast switching and energy storage applications.

Enhanced energy storage performance and thermal stability in relaxor ferroelectric BNKT-BBN solid solution ceramics

Bi0.5Na0.5TiO3 (BNT)-based relaxor ferroelectrics have attracted considerable interest over the past decades as candidate materials to replace lead-based piezoelectrics because of their environmental friendliness. Moreover, owing to their high maximum polarization and high-power density resulting from their relaxor activity, BNT-based relaxor ferroelectrics have attracted attention as potential candidates for energy storage. Herein, bismuth layer-structured BaBi2Nb2O9 (BBN) was introduced into the perovskite binary material system 0.78(Bi0.5Na0.5TiO3)-0.22(Bi0.5K0.5TiO3) (BNKT). Compared to pure BNKT ceramics, BNKT-BBN exhibited improved relaxor behavior and suppressed grain growth. Moreover, an increase in BBN content increased the breakdown strength. Consequently, the energy storage efficiency increased from 32 % to 58 %. In addition, the thermal stability (ΔWrec/Wrec) remained below ∼5 % in the temperature range from room temperature to 200 °C. The findings of this study demonstrated that the introduction of BBN into BNT-based relaxor ferroelectrics is an effective way to improve energy storage performance and high temperature stability.

Novel Sandwich-Structured Flexible Composite Films with Enhanced Piezoelectric Performance.

Piezoelectric poly(vinylidene fluoride) (PVDF) and its copolymers have been widely investigated for applications in wearable electric devices and sensing systems, owing to their intrinsic piezoelectricity and superior flexibility. However, their weak piezoelectricity poses major challenges for practical applications. To overcome these challenges, we propose a two-step synthesis approach to fabricate sandwich-structured piezoelectric films (BaTiO3@PDA/PVDF/BaTiO3@PDA) with significantly enhanced ferroelectric and piezoelectric properties. As compared to pristine PVDF films or conventional 0-3 composite films, a maximum polarization (Pmax) of 11.24 μC/cm2, a remanent polarization (Pr) of 5.83 μC/cm2, and an enhanced piezoelectric coefficient (d33 ∼ 14.6 pC/N) were achieved. Simulation and experimental results have demonstrated that the sandwich structure enhances the ability of composite films to withstand higher poling electric fields in comparison with 0-3 composites. The sandwich-structured piezoelectric films are further integrated into a wireless sensor system with a high force sensitivity of 288 mV/N, demonstrating great potential for movement monitoring applications. This facile approach shows great promise for the large-scale production of composite films with remarkable flexibility, ferroelectricity, and piezoelectricity for wearable sensing devices.

High energy storage of PbZrO3 antiferroelectric thin films via constructing phase composition

In this paper, we fabricated PbZrO3 (PZ) thin films by the way of sol–gel spin on LaNiO3 buffered SiO2/Si substrates, and annealed them at different given temperatures by rapid thermal annealing (RTA). By controlling annealing temperature, PZ thin films showed different microstructures and phase compositions, whose impact of electrical properties and energy storage performance were researched. According to the research findings, the phase composition of film presents a general rule with the decrease of annealing temperature: PZ thin films crystallize into perovskite phase, pyrochlore phase, and amorphous phase. The films annealed at 620 °C crystallized into a state of coexistence of pyrochlore phase and perovskite phases, which also show moderate recoverable energy density and the highest energy storage efficiency (8.7 J cm−3 and 93.1%). This energy storage performance can be attributed to the synergistic effect of high electric breakdown strength of dense pyrochlore phase structure and high maximum polarization of perovskite phase. The findings of this paper help to explain the influence of pyrochlore phase on the energy storge performance of thin films. Thus, it is useful way to improve the energy storage performance of thin films.

Hot-pressed Mn-doped Pb((Zr0.3Ti0.7)0.99Mn0.01)O3/polystyrene composites with improved dielectric and energy storage performance

Polymer composite films are superb dielectrics with high energy storage performance. Accordingly, herein we fabricated thick dumbbell-shaped 0–3 composites by incorporating Pb((Zr0.3Ti0.7)0.99Mn0.01)O3 (PMZT) as filler (0 –20% by weight) into a polystyrene (PS) matrix, using a two-step, solvent-free method involving melt mixing and subsequent hot pressing. The effects of processing parameters, acceptor doping in the filler, and filler content on the thermal, dielectric, and energy storage properties of the composites were investigated. IR spectroscopy and X-ray diffraction studies confirm the successful integration of the perovskite PMZT ceramic into the PS matrix. Notably, the composite morphology displayed a uniform distribution of filler particles, devoid of voids or agglomerates, indicating effective filler reinforcement. Mn ions acting as acceptor dopants in the ceramic filler, enhance the dielectric constant of the PMZT/PS composites while significantly minimizing the dielectric loss. The hot-pressing method promotes the alignment of dipoles of the filler particles within the composites, leading to stronger polarization and enhanced overall dielectric and ferroelectric response. Remarkably, the 20 wt% PMZT/PS composite exhibits an increased maximum polarization of 0.42 µC/cm2 and an 83% energy storage efficiency, making it a promising candidate for energy storage application.

Tunable d33/d33* for MPB (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 lead-free piezoceramic by crystallographic texturing approach

The morphotropic phase boundary (MPB) Ba0.85Ca0.15Zr0.10Ti0.90O3 composition is successfully transferred into <001>-textured ceramic having Lotgering factor f-74 % (abbreviated as BCZT-T74) using high aspect ratio BaTiO3-template particles via templated grain growth (TGG) method. The microstructural aspects reveal the distinctive grain growth formation for non-textured (BCZT-NT) and textured (BCZT-T74) ceramics; confirming the proper grain growth formation for textured ceramics. The polarization behavior was tested at 1 Hz, 5 Hz, and 10 Hz electric field frequencies by applying a voltage bias of 1000 V; the BCZT-NT ceramics show more variation in remnant polarization (Pr) as well as maximum polarization (Pmax) peak position while BCZT-T74 ceramics exhibit nearly steady values. The frequency-dependent variation in Pr (i.e. ΔPr) for non-textured and textured BCZT ceramics is ±11.08 % and ±3.25 % respectively in the frequency range 1Hz–10Hz at an applied voltage bias of 1000 V. The bipolar strain-electric field (S-E) butterfly loop evidences the typical piezoelectric nature; for both non-textured and textured BCZT ceramics having the effective piezoelectric strain coefficient d33* of 576 pm/V and 657 pm/V respectively. The BCZT-NT and BCZT-T74 ceramics revealed the average positive strain % values of 0.063 % and 0.1123 % and negative strain % values of 0.003985 % and 0.02281 % respectively at the applied voltage 1000 V functioning at 1Hz. The enhancement in negative strain% for BCZT-T74 ceramics is > 5.70 times higher than BCZT-NT ceramics. The variation in positive strain (i.e. ΔS+ve) and variation in negative strain (i.e. ΔS-ve) for non-textured ceramics is ±11.74 % and ±67.34 %, however, for textured ceramics is only ±3.33 % and ±5.00 % respectively. The BCZT-NT and BCZT-T74 ceramics exhibit the piezoelectric charge coefficient (d33) of 370 pC/N and 520 pC/N (1.4 times that of BCZT-NT ceramics) respectively. The electrostrictive coefficient (Q33) of BCZT-T74 ceramics is 0.039 m4/C2, which is > 2 times higher than BCZT-NT ceramics as well as commercially used toxic PZT-5H ceramics. Therefore, less variation in a strain, as well as polarization nature with varying frequencies and enhancement in piezo properties, suggests the present textured MPB BCZT-T74 ceramics is a promising candidate for piezoelectric devices functioning at the wide range of applied electric field frequencies.

Concurrent existence of magneto-electric coupling and electro-optic Kerr effect in perovskite-based ternary composites for energy reservoirs

Multiferroics, specifically magneto-electric materials that couple the ferroelectric and ferromagnetic responses, have boosted researchers' interest in fabricating energy storage devices. For this purpose, we synthesized the perovskite-based triphasic composites using sol–gel auto- combustion and solid–state reaction route. The presence of pure perovskite phases and lattice parameters were noted by X-ray diffraction analysis. Further, Rietveld’s refinement confirmed the precision of phase analysis with a high degree of goodness of fit. The homogenous and uniform growth of grains for 0.1BiFeO3 + 0.7BaTiO3 + 0.2Nd0.5Dy0.5MnO3 composite was seen by field emission scanning electron microscope and scanning transmission electron microscope. The perfect match between empirical elemental composition and prepared composites was determined by energy-dispersive X-ray spectroscopy. The highest remanent, maximum polarization, recoverable energy density, and ferroelectric efficiency were observed for the composite mentioned above. Furthermore, mathematical modeling via Python was carried out with ferroelectric data, and a mathematical relation was derived between the electric field and dielectric constant to observe the electro-optic Kerr effect. Similarly, the above-mentioned composite was seen with the highest coercive field, remanent, and maximum magnetization by M–H loops. Finally, the variation in polarization by changing the magnetic field confirmed M-E coupling and declared this 0.1BiFeO3 + 0.7BaTiO3 + 0.2Nd0.5Dy0.5MnO3 triphasic composite as best candidate for energy storage devices.

Modulating Quantum Well Width of Ferroelectric Ruddlesden–Popper Perovskites for Flexible Light Communication Device

Abstract2D Ruddlesden–Popper perovskites exhibit significant ferroelectricity due to the spontaneous polarization of organic molecules. By modulating the quantum well width in 2D Ruddlesden–Popper perovskites BA2MAn‐1PbnBr3n+1, a series of perovskites are adopted to realize adjustable polarization intensity and bandgap width. It is found that when n = 3, perovskite has the maximum polarization strength and optimal optoelectronic performance. In addition, flexible photodetectors with high mechanical stability are successfully fabricated based on n = 3 perovskite microplates. The fabricated flexible photodetectors exhibit high responsivity of 920 mA W−1 and detectivity of 1.02 × 1011 Jones, along with excellent flexibility and stability. After 3000 bending cycles, the photocurrent of n = 3 perovskites photodetector remains 81.8% of initial state. Besides, the photocurrent of n = 3 perovskites increase by 33 and 34 times after polarization at 0 and 3 V, respectively. And n = 3 perovskites exhibit a high polarization sensitivity with a current ratio of 2.09. On the basis of controllable regulation of the photocurrent through polarization, the application of flexible decoding optoelectronic devices by utilizing the correspondence between optical signals before and after polarization and binaries is achieved. These findings highlight the potential of modulating quantum well width in 2D Ruddlesden–Popper perovskites as a promising strategy for designing next‐generation flexible optoelectronic devices.

Enhanced magnetoelectric coupling effect in Mg-doped Y-type hexaferrite BaSrCo2-xMgxFe11.1Al0.9O22 ceramics

The influences of Mg doping on the magnetic order structure and magnetoelectric (ME) effect were investigated in Y-type hexaferrite BaSrCo2-xMgxFe11.1Al0.9O22 (x = 0.00, 0.25, 0.50, 0.75, 1.00) ceramics. The results revealed that the Mg doping could increase the magnetic phase transition temperature. The optimal magnetic-driven electric polarization could be obtained at x = 0.25 ceramic, exhibiting a maximum electric polarization of 16.22 μC/m2 and a ME coefficient of 203 ps/m at 100 K. The stability of reversible electric polarization was demonstrated via the measurement of continuous magnetic field cycles. Moreover, the ME phase diagram was established by measuring the magnetic dielectric properties. Finally, a possible Mg-tune magnetic structure was proposed to explain the enhanced ME effect.

Achieving high energy storage density and excellent stability in BiScO3 modified BaTiO3-based ceramics

High-performance dielectric energy storage ceramics has been brought to the fore by data as a result of the rapid rise in new energy development. The dielectric energy storage materials that can withstand harsh environments while having excellent energy storage performance, large breakdown strength, and maximum polarization is highly demanding. Herein, we fabricated the BiScO3 (BS) modified 0.88(Ba0.6Ca0.4)TiO3-0.12Bi[Mg2/3(Nb0.85Ta0.15)1/3O3] (BCT-BMNT) ceramics with excellent energy storage performance. The experimental results revealed that the breakdown strength of BCT-BMNT-xBS ceramics can be substantially increased by careful engineering of the grain uniformity induced by the incorporation of the BS. The BCT-BMNT-0.2BS ceramic exhibited a considerably optimal recoverable energy storage density of 5.75 J/cm3 along with a high energy efficiency of 89.63 % at 650 kV/cm. Moreover, this sample showed good stability in the temperature range of 20–160 °C and frequency range of 1–500 Hz and excellent fatigue resistance up to 105 cycles. Regarding the pulsed performance, as-prepared sample exhibited excellent power density of 145.30 MW/cm3 and current density of 937.43 A/cm2. Meanwhile, it showed a fast discharge time (t0.9) of 50.20 ns under the electric field of 460 kV/cm. This study demonstrates the crucial role that BS doping plays in improving the energy storage capabilities of BT-based lead-free ceramics, which pave the way for the use of BT-based ceramics in the field of energy storage.

Acoustic sensor based on a PVDF-TrFE/BTO composite structure with improved ferroelectric and piezoelectric properties

Ferroelectric composite structures of poly (vinylidene fluoride-co-trifluoroethylene)/ barium titanate (PVDF-TrFE/BTO) were prepared using a solvent casting method and altered using electrical and mechanical modes to improve their ferroelectric characteristics. The PFM and P-E loop analytic studies validated the enhanced ferroelectric and piezoelectric capabilities of the modified composite structures following mechanical stretching and electrical poling. The stretched and poled samples (PT-BT-s-p) were able to achieve a maximum saturated polarization of 5.98 µC/cm2 with suitable saturation loops and domain switching points. The presence of ferroelectric domains was further confirmed by the PFM amplitude and PFM phase graphs of the PT-BT-s-p composite structures. Furthermore, the suggested composite structure achieved a maximum piezoelectric coefficient (d33) value of 11 pC/N. Finally, a lab-scale experiment with a sound wave sensing application was performed and seen with superior outcomes with varying waveforms, amplitudes, and frequencies, making it a promising contender for future sensory devices.

The polarisation properties of the HD 18327 debris ring. Evidence for sub-micron particles from scattered light observations

Polarisation is a powerful remote-sensing tool to study the nature of particles scattering the starlight. It is widely used to characterise interplanetary dust particles in the Solar System and increasingly employed to investigate extrasolar dust in debris discs' systems. We aim to measure the scattering properties of the dust from the debris ring around at near-infrared wavelengths. We obtained high-contrast polarimetric images of in the H band with the SPHERE / IRDIS instrument on the Very Large Telescope (ESO). We complemented them with archival data from HST / NICMOS in the F110W filter reprocessed in the context of the Archival Legacy Investigations of Circumstellar Environments (ALICE) project. We developed a combined forward-modelling framework to simultaneously retrieve the scattering phase function in polarisation and intensity. We detected the debris disc around in polarised light and total intensity. We measured the scattering phase function and the degree of linear polarisation of the dust at 1.6 in the birth ring. The maximum polarisation is $23.6&lt;!PCT!&gt; 2.6&lt;!PCT!&gt;$ and occurs between a scattering angle of $70^ and $82^ We show that compact spherical particles made of a highly refractive and relatively absorbing material in a differential power-law size distribution of exponent $-3.5$ can simultaneously reproduce the polarimetric and total intensity scattering properties of the dust. This type of material cannot be obtained with a mixture of silicates, amorphous carbon, water ice, and porosity, and requires a more refracting component such as iron-bearing minerals. We reveal a striking analogy between the near-infrared polarisation of comets and that of The methodology developed here combining VLT/SPHERE and HST/NICMOS may be applicable in the future to combine the polarimetric capabilities of SPHERE with the sensitivity of JWST.

Structural heterogeneity induced enhancement of physical properties in Sm‐modified K0.5Na0.5NbO3

AbstractDoping of suitable metal ions in ferroelectric oxides modifies the physical properties and can induce additional functionalities. Here, we present a detailed study on the effects of Sm concentration on the structural, dielectric, ferroelectric, and piezoelectric properties of ((K0.5Na0.5)1−3xSmx)NbO3 (KNSN) (0.00 ≤ x ≤ 0.02) ceramics. X‐ray diffraction and Raman spectroscopic analysis indicate that KNSN ceramics exhibit the single‐phase orthorhombic (Amm2) structure for x = 0.00 and the coexistence of orthorhombic and tetragonal (Amm2 + P4mm) structure for the composition range 0.005 ≤ x ≤ 0.02. The tetragonal phase fraction increases with an increase in Sm concentration. We observed dielectric relaxation behavior in KNSN at orthorhombic to tetragonal (TO–T) phase transition temperature, and its origin can be attributed to the structural heterogeneity at the inter‐ferroelectric phase boundary. Increasing Sm concentration leads to the broadening of the ferroelectric phase transition peaks. Further, the structural heterogeneity of the ceramics was seen from the slope of the dielectric constant versus log frequency and central peak behavior of Raman spectra at room temperature (RT). The study reveals that x = 0.005 shows maximum dielectric constant (Ɛr = 583), remanent polarization (2Pr = 57.02 μC/cm2), and piezoelectric coefficient (d33 = 94 pC/N) at RT and is associated with increased local structural heterogeneity due to Sm doping.

Achieving ultrahigh energy storage density under low electric field in (Na0.5Bi0.5)TiO3-based relaxor ferroelectric ceramics via a synergistic optimization strategy

Lead-free dielectric ceramic capacitors are attracting much interest in pulse power systems owing to their fast charge/discharge rate and high power density. However, their development towards integration and miniaturization in electronic devices has been severely impeded by low energy storage performance (ESP) under low electric field (E). Herein, a synergistic optimization strategy of composition design and domain engineering was proposed in the Bi(Mg0.5Hf0.5)O3-modified Na0.5Bi0.5TiO3-Sr0.7Bi0.2Ca0.1TiO3 ceramics [(1-x)(NBT-SBCT)-xBMH], aiming to improve ESP at low E. As a result, an ultrahigh recoverable energy density (Wrec) of ∼5.9 J/cm3 and a high efficiency (η) of ∼85 % can be obtained in x = 0.20 ceramics under a low E of 260 kV/cm, which is superior to previously reported lead-free materials under the equivalent E. The outstanding Wrec is mainly ascribed to the ultrahigh polarization discrepancy (ΔP) of ∼50.8 μC/cm2 since the rich hybridization of Bi 6 s and O 2p orbitals maintains a maximum polarization and the addition of Mg2+ and Hf4+ transforms the long-range ferroelectric order into polar nanoregions (PNRs) with good relaxation characteristics. Moreover, a fast discharge time (∼62 ns), good temperature (20–120 °C) and frequency (1–103 Hz) stabilities, and excellent fatigue resistance (×105 cycles) can be concurrently realized in x = 0.20 ceramics. These results demonstrate the promising strategy of developing low E lead-free ceramics for dielectric energy storage.

Enhancement of dielectric and ferroelectric properties of (Sr, Ni) Co-doped BaTiO3 ceramics

In the present study, systematic investigations on dielectric and ferroelectric properties of pure and (Sr, Ni) co-doped BaTiO3 nanocrystalline powder samples fabricated via microwave-assisted co-precipitation method have been reported. XRD patterns divulge the formation of mono-phase tetragonal crystal structure with P4mm space group. The fingerprint bands in the FTIR spectra further assure the formation of desired crystal structure. The dielectric responses have been examined by virtue of the universal dielectric response mechanism with remarkable improvement in the dielectric properties for the (Sr, Ni) co-doped sample. The P-E loop measurement corroborates ferroelectricity in the system and augmentation in the maximum polarization for the co-doped sample. The improved dielectric and ferroelectric properties in (Sr, Ni) co-doped BaTiO3 suggest its potential in various technological applications.